When finishing plasterboard or plasterboard, the degree of softness you need to deliver is defined by the nature of the final decoration. The European Q rating helps you assess what level of drywall finish quality is required and what each of these four Q levels entails.
A glossy wallpaper decoration requires a more advanced surface finish than a tile coating or a coarse texture. But how can you determine what level of drywall finish a specific job requires? The European Q classification serves as a guideline. It helps you assess the level of quality, or Q-level, of drywall finish that is required, and what each of these four Q-levels entails. Being clear about the Q-level that can be expected also avoids arguments and misunderstandings about the final result delivered.
A specific Q level of drywall finish for each surface decoration
In the Q1 to Q4 classification for drywall finishing, the lowest level is the most basic finishing level. Look for the highest level of quality when you need the smoothest possible surfaces with high visual requirements.
- Q1 for surfaces without decorative requirements
A Q1 plasterboard finish is sufficient when no decorative requirements apply. Q1 surfaces can be covered with thick-layered tile, board, or plaster.
- Q2 for minimal surface smoothness
Q2 prepares plasterboard surfaces for structured wallpaper, structured paint and manually applied coatings with wool or structured rollers, as well as thick top coatings with a particle size greater than 1 mm.
- Q3 when demanding visual requirements for the surface are applied
Q3 prepares plasterboard surfaces for structured wall coverings and thin paint coatings as well as top coatings with a particle size of less than 1 mm.
- Q4 prepares surfaces for the highest decorative standards
The Q4 finish meets the highest visual requirements of the surface. It allows you to decorate with glossy wallpapers, paints or layers of varnish, as well as stucco marble and similar finishes.
What drywall finishing steps does each Q level involve?
Once the last layer of decoration is determined, you will know what level Q is needed for the drywall finish. But what does each Q level imply?
Q1 finishing steps to deliver bonded drywall surfaces
After mounting the plasterboard, follow the steps below to obtain a Q1 finish:
- Compound joint applique
- Apply tape over the joint compound.
- Cover visible parts of fasteners
- Remove excess joint compound
Q2 finishing steps to deliver drywall surfaces with minimal smoothness
A Q2 finish involves a perfect transition layer over a Q1 finish:
- Apply joint compound on top of Q1
- Finish to achieve a seamless transition from the seam area to the plate surface
- Sanding may be necessary afterwards
- Repeat the above on fasteners, corners, and joints filled with joint compound.
It is generally assumed that a Q2 finish is required, unless otherwise agreed by the contractor and customer.
Q3 finishing steps to deliver extra-smooth drywall surfaces
Applying a Q3 finish requires a wider finish above the Q2 finish, followed by a full plasterboard finish:
- Apply a wider finish over the Q2 finished surface
- Finish the entire surface of the plasterboard to fill all pores.
- Sanding may be necessary afterwards
Q4 finishing step to create smoothed drywall
To achieve Q4, you need to apply a full coat of smoothing over a Q2 finish:
- The smoothing layer should be at least 1 mm thick
- The smoothing coat should be applied over the entire surface of the drywall.
Q4 only requires one additional step in addition to a Q2 finish. However, keep in mind that smoothing is a difficult art to master, as it is necessary to deliver a surface with minimal marks and traces. Marks and traces must also be invisible with side lighting. Therefore, it is advisable to do a test for Q4 level projects, taking into account the expected lighting conditions of the decorated surface.
